1. Field of the Invention
This invention relates to an abrasive tape for use in accurate polishing of a magnetic head for a magnetic recording and reproducing apparatus. This invention particularly relates to an abrasive tape for use in smooth finishing of a video magnetic head or a high grade audio magnetic head.
2. Description of the Prior Art
Video or high grade audio magnetic heads are required to have very smooth tape sliding surfaces. Therefore, in general, in the process of making the magnetic head, the tape sliding surface is given a smooth finish by use of an abrasive tape after rough grinding. The abrasive tape comprises a flexible non-magnetic substrate and fine abraisve particles or the like coated thereon, and can accurately polish the tape sliding surface of the magnetic head by snugly fitting to the curved shape thereof.
As the abrasive tape, there has heretofore been known, for example, a cleaning tape as disclosed in Japanese Unexamined Patent Publication No. 53(1978)-102017, which comprises a substrate, and a mixture of an abrasive material consisting of zinc oxide (ZnO) or the like with a binder consisting of a vinyl chloride-vinyl acetate copolymer or the like kneaded together and coated onto the substrate.
However, the purpose of the aforesaid tape is mainly to remove dust or the like from the magnetic head. Since zinc oxide or the like having a Mohs hardness within the range of approximately 4 to 5 is used as the abrasive material for satisfying the purpose, the hardness of the abrasive material is too low to satisfy the requirements of the tape for polishing the magnetic head.
Also, the conventional binder using a vinyl chloride-vinyl acetate copolymer or the like is not so much flexible. Therefore, with the abrasive tape using such a binder, it is impossible to substantially polish a curved portion of the magnetic head, and therefore it is not always possible to improve the characteristics of the video or high grade audio magnetic head which is required to exhibit high sensitivity and a high S/N ratio.